Table 813: Special conditions
Condition
Description
U3P connected to real measurements
The function can work with any two voltage
channels connected but it is recommended
to connect all three voltage channels.
Improper analog channel configuration causes a validation error if the analog
channels are not completely configured or they do not match with certain settings.
For troubleshooting, check the contents of this chapter and also the preprocessing
blocks in this document. The configuration can be written to the protection relay
once the mismatch is corrected.
4.5.4.5
Operation principle
The function can be enabled and disabled with the
Operation setting. The
corresponding parameter values are "On" and "Off".
The operation of PSPTOV can be described with a module diagram. All the modules
in the diagram are explained in the next sections.
OPERATE
Level
detector
BLOCK
START
t
Timer
U3P
U_A
U_B
U_C
Blocking
logic
Figure 489: Functional module diagram
Level detector
The calculated positive-sequence voltage is compared to the set
Start value setting.
If the value exceeds the set
Start value, the level detector enables the timer. The
Relative hysteresis setting can be used for preventing unnecessary oscillations if the
input signal slightly varies from the
Start value setting. After leaving the hysteresis
area, the start condition has to be fulfilled again and it is not sufficient for the
signal to only return to the hysteresis area.
Timer
Once activated, Timer activates the
START
output. The time characteristic is
according to DT. When the operation timer has reached the value set by
Operate
delay time, the
OPERATE
output is activated if the overvoltage condition persists.
If the positive-sequence voltage normalizes before the module operates, the reset
timer is activated. If the reset timer reaches the value set by
Reset delay time, the
operate timer resets and the
START
output is deactivated.
Protection functions
1MRS759142 F
872
REX640
Technical Manual